The UK government said it would consider allowing biotechnology companies to keep the sites of genetically modified (GM) crop trials secret, following incidents by Greenpeace on a trial site in Lyng, Norfolk, last week.

At present the location of sites registered to carry out GM trials, and the type of trials being conducted, are public knowledge. A map of the sites is available on the Environment Department's Web site, and companies planning to carry out trials are obliged to place advertisements in local papers before starting up.

Last week's raid was on a field of GM maize planted by the Hoechst/Schering agbio company AgrEvo UK Ltd., and was the third farm-scale experiment to be disrupted in the UK in the past eight weeks.

Greenpeace argued that the pollen from GM crops will cross-pollinate with other species. It justified the action by saying its "decontamination unit" had "removed GM pollution." Twenty-eight Greenpeace activists, including the pressure group's executive director, Peter Melchett, were arrested as the raid was in progress.

Other GM sites attacked recently include AstraZeneca plc's research center in Jealotts Hill, Bracknell. There, poplar trees, engineered to have a low lignin content, were cut down. The irony is that the company said these trees will be environmentally friendly as the low lignin content will reduce the need for bleaching agents when they are processed into paper.

The government insisted trials must be allowed to proceed since that is the only way to obtain data on the environmental impact of GM crops. But Greenpeace argued that making the sites secret will increase public disquiet about GM crops.